1. Field of the Invention
This invention relates to apparatus for the adsorption of vaporous or gaseous impurities which can be adsorbed in sorption filters, from air or other gases as well as to their desorption by an inert gas produced by stoichiometric combustion of coal, coke or hydrocarbons after the sorbents used in the sorption filter have been loaded with adsorbed impurities to a certain level, as well as a method for operating them safely.
2. Description of the Prior Art
Sorption filters are employed in process engineering for separating gaseous or vaporous mixtures or substances. They have become important, in particular, in the purification of exhaust gases and exhaust air where organic substances such as for instance solvents or also substances which are malodorous and offend the olefactory senses of the population in the surrounding neighborhood. Separation of such substances by adsorption is known from the solvent recovery installations used for this purpose. It is likewise known to remove foul smelling substances from exhaust air or exhaust gas through adsorption. The problem of desorption is therefore dealt with by the known water vapor desorption in the solvent recovery installations, by stack gas desorption or by desorption with inert gas specially generated for this purpose. Typical for this are method and apparatus such as are described, for instance, in the U.S. Pat. Nos. 3,853,985; 3,905,783; 3,930,803 and German Published Prosecuted Patent Application No. P 22 48 267. In these cases the sorption filter, after a certain loading with adsorbable substances is reached, is switched off the gas or air stream and is desorbed by an inert gas generated by stoichiometric combustion of coal, coke or hydrocarbons. To improve the flushing of desorbate, this inert gas is advantageously conducted in a closed loop, and part of the inert gas loaded with desorbate is branched off and fed either to thermal after-combustion or to a cooler. The branched-off gas is replaced by freshly generated inert gas. This freshly generated gas therefore carries with it the heat energy which is required for the desorption.